break one's back

This continual lifting of the heavily loaded sledges is calculated to break one’s back; but better times are coming, perhaps.

The beds were so low as to break one's back, and had iron sides which were always in the way; and when we came to the end of our sheets—well, we came to the end of them, and that was all.

"My goodness," he whispered to Ned, "that all-fours' work is enough to break one's back, Ned."